1. Field of the Invention
This invention relates to an improved interfacial polycondensation process of preparing a polycarbonate by reacting a dihydric phenol, which may be sterically hindered, with a carbonyl halide in the presence of a polycondensation catalyst, the improvement wherein the catalyst is a quaternary-phosphonium amino halide catalyst.
2. Description of the Prior Publications and/or Art
In general, interfacial polycondensation publications including "The Encyclopedia of Polymer Science, Vol. 10 (1969), "Chemistry and Physics of Polycarbonates, Polymer Reviews," H. Schnell, Vol. 9, John Wiley & Sons, Inc. (1964); "Polycarbonates," Christopher N. Fox, Rheinhold Corporation of New York, (1962); among other publications, including numerous and foreign patents, e.g., U.S. Pat. Nos. 3,227,681; 3,275,601; 3,789,347; 3,879,345; and West German Offenlegungsschrift No. 29 01 668, report that generally effective polycondensation catalysts comprise tertiary amines or quaternary organic bases or salts thereof e.g., triethylamine, pyridine, tribenzylammonium chloride, etc., among others.
Some of the benefits associated with the process of the present invention include (1) the use of substantially reduced amounts of polycondensation catalyst to effect interfacial polycondensation, (2) the formation of polycarbonates having an improved M.sub.w /M.sub.n value, the ability to recycle the polycondensation catalyst, and reduced carbonyl halide requirements for making sterically hindered polycarbonates.
3. Description of the Invention
The present invention embodies an improved interfacial polycondensation process for the preparation of aromatic polycarbonate by reacting dihydric phenol with carbonyl halide in the presence of a quaternary-phosphonium amino halide polycondensation catalyst.
The expression "quaternary-phosphonium amino halide" as employed herein and in the claims (hereinafter also referred to as "aminoalkyl tri-substituted phosphonium compounds") includes, among others, any quaternary phosphonium compound having the structural formula: ##STR1## wherein independently each R is an alkyl, cycloalkyl or aryl group, R.sub.a is a divalent alkylene including cycloalkylene groups, X is a halogen radical and R.sub.b and R.sub.c are selected from the same or different alkyl or cycloalkyl groups.
Among the "quaternary-phosphonium amino halides" of the present invention are compounds which contain R, R.sub.a and R.sub.b as defined above.
Radicals included by R of formula (1) are a C.sub.1-10 alkyl, C.sub.4-10 cycloalkyl, or C.sub.6-10 aryl group, including mixtures thereof; R.sub.a is a C.sub.3-12 alkylene or C.sub.4-12 cycloalkylene group, including mixtures thereof; R.sub.b is a C.sub.1-10 alkyl or C.sub.4-10 cycloalkyl group, including mixtures thereof; and R.sub.c is a C.sub.1-10 alkyl or C.sub.4-10 cycloalkyl group, including mixtures thereof.
Included in the quaternary-phosphonium amino halide salts of formula (I) are, for example, the following:
(3-dimethylaminopropyl)triphenylphosphonium bromide hydrobromide, PA1 (3-diethylaminopropyl)triphenylphosphonium bromide hydrobromide, PA1 (4-didecylaminocyclohexyl)tributylphosphonium chloride hydrochloride, PA1 (5-dioctylaminopentyl)diphenylphosphonium chloride hydrochloride, PA1 (10-dimethylaminodecyl)phenyldibutylphosphonium bromide hydrobromide, PA1 (3-methylethylaminopropyl)tributylphosphonium bromide hydrobromide, PA1 (4-methylbutylaminobutyl)tributylphosphonium bromide hydrobromide, and PA1 (7-cyclohexylpropylaminoheptyl)triphenylphosphonium iodide hydroiodide, etc. PA1 resorcinol; PA1 4,4'-dihydroxy-diphenyl; PA1 1,6-dihydroxy-naphthalene; PA1 2,6-dihydroxy-naphthalene; PA1 4,4'-dihydroxy-diphenyl methane; PA1 4,4'-dihydroxy-diphenyl-1,1-ethane; PA1 4,4'-dihydroxy-diphenyl-1,1-butane; PA1 4,4'-dihydroxy-diphenyl-1,1-isobutane; PA1 4,4'-dihydroxy-diphenyl-1,1-cyclopentane; PA1 4,4'-dihydroxy-diphenyl-1,1-cyclohexane; PA1 4,4'-dihydroxy-diphenyl-phenyl methane; PA1 4,4'-dihydroxy-diphenyl-2,4-dichlorophenyl methane; PA1 4,4'-dihydroxy-diphenyl-p-isopropylphenyl methane; PA1 4,4'-dihydroxy-diphenyl-2,2-propane; PA1 4,4'-dihydroxy-3-methyl-diphenyl-2,2-propane; PA1 4,4'-dihydroxy-3-cyclohexyl-diphenyl-2,2-propane; PA1 4,4'-dihydroxy-3-methoxy-diphenyl-2,2-propane; PA1 4,4'-dihydroxy-3,3'-dimethyl-diphenyl-2,2-propane; PA1 4,4'-dihydroxy-3,3'-dichloro-diphenyl-2,2-propane; PA1 4,4'-dihydroxy-diphenyl-2,2-butane; PA1 4,4'-dihydroxy-diphenyl-2,2-pentane; PA1 4,4'-dihydroxy-diphenyl-2,2-(4-methyl pentane); PA1 4,4'-dihydroxy-diphenyl-2,2-n-hexane; PA1 4,4'-dihydroxy-diphenyl-2,2-nonane; PA1 4,4'-dihydroxy-diphenyl-4,4-heptane; PA1 4,4'-dihydroxy-diphenyl phenylmethyl methane; PA1 4,4'-dihydroxy-diphenyl-4,4-chlorophenylmethyl methane; PA1 4,4'-dihydroxy-diphenyl-2,5-dichlorophenylmethyl methane; PA1 4,4'-dihydroxy-diphenyl-3,4-dichlorophenylmethyl methane; PA1 4,4'-dihydroxy-diphenyl-2-naphthylmethyl methane; PA1 4,4'-dihydroxy-tetraphenyl methane; PA1 4,4'-dihydroxy-diphenyl-1,2-ethane; PA1 4,4'-dihydroxy-diphenyl-1,10-n-decane; PA1 4,4'-dihydroxy-diphenyl-1,6(1,6-dioxo-n-hexane); PA1 4,4'-dihydroxy-diphenyl-1,10(1,10-dioxo-n-decane); PA1 bis-p-hydroxy-phenylether-4,4'-biphenyl; PA1 .alpha.,.alpha.,.alpha.',.alpha.'-tetramethyl-.alpha.,.alpha.'-di(p-hydroxy phenyl)-p-xylylene; PA1 .alpha.,.alpha.,.alpha.',.alpha.'-tetramethyl-.alpha.,.alpha.'-di(p-hydroxy phenyl)-m-xylylene; PA1 4,4'-dihydroxy-3,3'-dimethyl-diphenyl methane; PA1 4,4'-dihydroxy-2,2'-dimethyl-diphenyl methane; PA1 4,4'-dihydroxy-3,3'-dichloro-diphenyl methane; PA1 4,4'-dihydroxy-3,3'-dimethoxy-diphenyl methane; PA1 4,4'-dihydroxy-2,2',5,5-tetramethyl-diphenyl methane; PA1 4,4'-dihydroxy-2,2'-dimethyl-5,5-diisopropyldiphenyl methane; PA1 4,4'-dihydroxy-2,2'-dimethyl-5,5'-dipropyl-diphenyl methane; PA1 4,4'-dihydroxy-diphenyl-5,5-nonane; PA1 4,4'-dihydroxy-diphenyl-6,6-undecane; PA1 4,4'-dihydroxy-diphenyl-3,3-butanone-2; PA1 4,4'-dihydroxy-diphenyl-4,4-hexanone-3; PA1 4,4'-dihydroxy-diphenylmethyl-4-methoxy-phenyl methane; PA1 4,4'-dihydroxy-diphenyl ether; PA1 4,4'-dihydroxy-diphenyl sulfide; PA1 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide; PA1 4,4'-dihydroxy-diphenyl sulfoxide; PA1 4,4'-dihydroxy-diphenyl sulfone; PA1 4,4'-dihydroxy-3,3'-dichlorodiphenyl sulfone; PA1 2,2-bis(4-hydroxy-phenyl)-1-chloroethylene; PA1 2,2-bis(4-hydroxy-phenyl)-1,1-dichloroethylene; and PA1 2,2-bis(4-hydroxy-phenyl)-1,1-dibromoethylene, etc. PA1 1,1-bis(4-hydroxy-3,5-dimethylphenyl)methane; PA1 2,4'-dihydroxy-3,3',5,5'-tetramethylphenyl methane; PA1 1,1-bis(3,5-diethyl-4-hydroxyphenyl)methane; PA1 1,1-bis(3,5-diisopropyl-4-hydroxyphenyl)methane; PA1 1,1-bis(3,5-dibromo-4-hydroxyphenyl)methane; PA1 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)ethane; PA1 1,1-bis(3-methyl-5-ethyl-4-hydroxyphenyl)ethane; PA1 1,1-bis(3,5-diethyl-4-hydroxyphenyl)ethane; PA1 2,2-bis(3-methyl-5-ethyl-4-hydroxyphenyl)propane; PA1 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane; PA1 2,2-bis(3,5-diisopropyl-4-hydroxyphenyl)propane; PA1 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane; PA1 2,2-bis(3,5-dibromo-4-hydroxyphenyl)butane; PA1 2,4'-dihydroxy-3,3',5,5'-tetramethylbenzophenone; PA1 4,4'-dihydroxy-3,3',5,5'-tetraethyldiphenyl sulfone; PA1 4,4'-dihydroxy-3,3',5,5'-tetrabutyldiphenyl sulfide; PA1 4,4'-dihydroxy-3,3',5,5'-tetramethyldiphenyl ether; PA1 4,4'-dihydroxy-3,3',5,5'-tetrapropyldiphenyl sulfoxide; PA1 2,2'-bis(3,5-dimethyl-4-hydroxyphenyl)-1-chloroethylene; PA1 2,2'-bis(3,5-dimethyl-4-hydroxyphenyl)-1,1-dichloroethylene; and PA1 2,2'-bis(3,5-dibutoxy-4-hydroxyphenyl)-1,1-dibromomethylene; etc. PA1 (1) introducing a carbonyl halide into agitated plural-phase mixture comprising a dihydric phenol, an inert organic solvent, water alkali metal hydroxide and a quaternary phosphonium amino halide, where there is utilized from 0.05 to 3% by weight of the quaternary phosphonium amino halide, based on the weight of the dihydric phenol and sufficient alkali metal hydroxide to provide a pH of at least 10 in the resulting mixture and PA1 (2) recovering aromatic polycarbonate from the resulting mixture of (1).
The quaternary-phosphonium amino halides, hereafter for brevity also referred to as (Q-PAH) can be prepared by any method well known to those skilled in the art including the methods referenced in Great Britain No. 1,085,406. In general, a presently preferred method comprises the reaction of an .alpha.,.omega.-dihaloalkane with a tri-substituted phosphine to form a tetra-substituted phosphonium halide, which is subsequently reacted with an aliphatic secondary amine to form the desired catalyst species, i.e., an (.omega.-dialkylaminoalkyl)trisubstituted phosphonium compound.
The dihydric phenols used in the practice of the invention are well known to those skilled in the art as illustrated by D. W. Fox's U.S. Pat. No. 3,153,008 and can be illustrated by formula (2) set out hereafter: ##STR2## where R.sub.f is an alkylene, alkylidene including "vinylidene," cycloalkylene, cycloalkylidene or arylene linkages or a mixture thereof, a linkage selected from the group consisting of ether, carbonyl, amine, a sulfur or phosphorous containing linkage, Ar and Ar' are arene radicals, Y is bromine, chlorine or a monovalent alkyl or alkoxy group, each d represents a whole number from 0 up to a maximum equivalent to the number of replaceable hydrogens substituted on the aromatic rings comprising Ar or Ar', subject to the proviso that when d is equal to two or more, no more than one Y group is ortho-positioned relative to an --OH group, X is bromine, chlorine or a monovalent hydrocarbon group selected from the class consisting of alkyl, aryl and cycloalkyl including mixtures thereof, e represents a whole number of from 0 to a maximum controlled by the number of replaceable hydrogens on R.sub.f, aa, bb and cc represent whole numbers including 0, when bb is not zero, neither aa or cc may be zero, otherwise either aa or cc but not both may be 0, when bb is zero, the aromatic groups can be joined by a direct carbon bond. As utilized hereinafter, the term "sterically hindered bisphenol" or "sterically hindered dihydric phenol" preferably means dihydric within the scope of (2), where Y is a monovalent alkyl or alkoxy group, d represents a whole number up to a maximum equivalent to the number of replaceable hydrogens substituted on the aromatic rings comprising Ar or Ar' subject to the proviso that at least two Y groups are ortho positioned relative to each --OH group of each arene radical.
Sterically-hindered aromatic polycarbonate is shown as follows: ##STR3## where independently each R' is a C.sub.1-4 alkyl or alkoxy group, R.sub.g and R.sub.h are hydrogen or a C.sub.1-2 alkyl group, each Z.sub.a is hydrogen, chlorine or bromine, subject to the proviso that at least one Z.sub.a is chlorine or bromine, and x is a positive integer having a value greater than 1.
Some of the dihydric phenols of formula (2) are, for example,
Some of the sterically hindered dihydric phenols employed in the practice of the invention are as follows:
The expression "carbonyl halides" as employed herein and in the claims includes carbonyldichloride, more commonly known as phosgene, carbonyl dibromide, carbonyl diiodide, carbonyl difluoride, carbonylchlorofluoride, including mixtures thereof.
Some of the aromatic polycarbonates prepared by the process of this invention can be illustrated as follows: ##STR4## wherein R.sub.f, Ar, Ar', Y, X, d, e, aa, bb, and cc are as defined above and x' is a number of at least 2, preferably from 30 to 200 or higher, and often more preferably from 40 to 100.
The preferred aromatic polycarbonate are as follows: ##STR5## where independently each R" is hydrogen, bromine, chlorine or a C.sub.1-4 alkyl or alkoxy group, R.sub.g and R.sub.h are hydrogen or a C.sub.1-2 alkyl group, and Z.sub.a and x' are as previously defined.
There is provided by the present invention, a process of preparing aromatic polycarbonates which comprises
The process parameter related to pH is maintained throughout the course of the reaction, by any means, such as, optionally, by the initial addition of large excesses of alkali metal hydroxide including the substantially continuous addition of alkali metal hydroxide during the course of the reaction, e.g., concurrently with the carbonyl halide addition.
Any inert solvent can be used including medium polar solvents such as chlorobenzene, bromobenzene, orthodichlorobenzene, methylene chloride, 1,2-dichloroethane, iodobenzene, etc. and mixtures thereof. Preferably, the solvents employed are halogenated hydrocarbons, more preferably methylene chloride.
The interfacial polycondensation is carried out in any strongly basic reaction medium, i.e., pH 10 or higher, provided by the presence of a strong inorganic base, including mixtures thereof. Representative of basic species which can be employed are the following: basic quaternary ammonium, quaternary phosphonium or tertiary sulfonium hydroxide; alkali metal hydroxides; etc. Specific examples are tetramethyl ammonium hydroxide, tetraethyl phosphonium hydroxide, etc.; the lithium, sodium and potassium hydroxides; etc. Especially preferred are sodium or potassium hydroxide.
The amount of dihydric phenol and carbonyl halide which can be employed in the interfacial polycondensation reaction is not critical, subject to the proviso that the carbonyl halide is present in stoichiometric amounts at least sufficient to react with the hydroxy groups associated with the dihydric phenol. Preferably, the carbonyl halide is present in excess, i.e., in amounts of at least about 1.25 to 1.5 times the stoichiometric amounts required to completely couple all of the reactive dihydric phenol to form the desired aromatic polycarbonate.
Any amount of base can be employed subject to the proviso that the agitated two-phase mixture is maintained at a pH value in excess of about 10, preferably within the range of 10-12, an optionally, as high as 14. Generally effective mol proportions of base relative to the hydroxyl groups associated with the dihydric phenol are within the range of from about 2:1 to 5:1 and frequently preferably from about 2.1:1 to 3.1.
The amount of quaternary phosphonium amino halide catalyst which can be employed is not critical however, generally effective mol proportions relative to the dihydric phenol are within the range from about 0.025% to about 3.0% and preferably within the range of from about 0.05% to about 1.0% per mole of dihydric phenol.
The aromatic polycarbonate derived from the process of the present invention, preferably, exhibit an intrinsic viscosity of at least 0.3, and more preferably about 0.5 deciliters per gram (dl/g) as measured in either methylene chloride or chloroform or a similar solvent system at 25.degree. C. The upper intrinsic viscosity number is not critical, however, and will generally be about 1.5 dl/g. Especially useful polycarbonates generally have intrinsic viscosities within the range of from about 0.38 to about 0.7 dl/g. Preferably, the polycarbonates have a number average molecular weight of at least about 5000, and more preferably from about 10,000 to about 50,000 or higher. Polycarbonates of such molecular weight characteristics process easily in between about 450.degree. F. and 650.degree. F., and are generally suitable raw materials for the manufacture of filaments, fibers, films, sheets, laminates, and other thermoplastic articles of manufacture including reinforced articles employing conventional molding, extruding, etc., manufacturing techniques.